Incandescent lamp.



m. 67mm. 4 Patented Mar. I9, 901. r

B. A. rsssuwm. INBANDESGEM LAfiPH (Application filed Nov. 27, 1900.) (NoModel.) 5 Shoet-Sheet I,

F I E. I.

WITNESSES: A INVENTOR Atty.

No. 670,3I6. Patented Mar. l9, l90l. R. A. FESSENDEN.

INCANDESCENT LAMP.

(Application filed Nov. 27, 1900.) (No Model.) 5 Sheets$heet 2.

fivggjgs: 3 I6 INZSNTOR J H Atty.

No. 670,3l6. Patented Mar. |9,'l90|. R. A. FESSENDEN. INCANDESGENT LAMP.

(Application filed Nov. 27, 1900.]

(No Model.) 5 Sheets-Sheet 3,

INVENTOR No. 670,356. Patented Mar. i9, 190:; R. A. FESSENIJEN.

iNGANDESCENT LMflP.

(Application filed Nov. 27. 1900.;

5 Sheets-Sheet 4,

INVENTOQ N o. 670,3l6. Patented Mar. [9, I90I. n. A. FESSENDEN.

lNCANDESCENT LAMP.

(Application filed Nov. 27, 1900.)

5 Sheets8heet 5.

(No Model.)

FIGS.

lNVENTQR %\iV ITNESSE% lNrreo STATES PATENT OFFICE.

REGINALD A. FESSENDEN, OF ALLEGHENY, PENNSYLVANIA.

INCA'NDESCENT LAM P.

SPECIFICATION forming part of Letters Patent No. 670,316, dated March19, 1901. Ap lication filed November 27,1900. Serial No. 37,902, (Nmodel.)

To all whom, it may concern:

Be it known that I, REGINALD A. FEssEN- DEN, a citizen of the UnitedStates, residing at Allegheny, in the county of Allegheny and State ofPennsylvania, have invented or discovered certain new and usefulImprovements in Incandescent Lamps, of which improvements the followingis a specification.

The invention described herein relates to certain improvements inelectric incandescent lamps of the Nernst type employing as the sourceof light a pencil formed of a material which requires a preliminaryheating in order to render it conductive of the electric current,whereby the pencil is raised to and maintained at incandescence.

One object of the invention is to provide for the automatic reduction orcutting off of the current through the heating body or bodies as soon asthe pencil becomes conductive.

It is a further object of the invention to provide for the preliminaryheating of the li ght-givin g body by radiation and conduction frombodies heated by the passage of an electric current.

The invention is hereinafter more fully described and claimed.

In the accompanying drawings, forming a part of this specification,Figure 1 is a sectional elevation of one form of my improved lamp. Fig.2 is a diagrammatic view illustrating the invention. Fig. 3 is a detailview illustrating a manner of short-circuitingthe pencil. Fig. 4 is adiagrammatic View illustrating the manner of simultaneously heating allparts of the pencil. Fig.- 5 is a view similar to Fig. 4, illustrating amodification. Fig. 6 is a diagrammatic view illustrating the manner ofarranging the lamps in lighting groups. Fig. 7 illustrates a furthermodification of the arrangement shown in Figs. 4 and 5. Figs. 8 and 9are diagrammatic views illustrating the construction and arrangement forlamps for constant-voltage currents. In the practice of my invention Iemploy in this form of apparatus a transformer consisting of core 1, aprimary coil 2, which is connected to an alternating-current dynamo orother suitable source furnishing a current of unvarying amperage orhavinga constant value, and two secondary coils 3 and 4. Thistransformer is preferably arranged in the rent through the heater 7.

socket 5 of a lamp, and the circuit from the generator is controlled bya switch 6, of any suitable constructiomalso located in the lam psocketor adjacent thereto for house-lighting. A heater 7, of any suitableconstruction, is included in the circuit of the secondary coils 3 of thetransformer, and the pencil 8, preferably formed of magnesia, kaolin, orother ma terial conductive of electric currents only when heated abovenormal temperature, is included in the circuit of the secondary coil 4of the transformer. The secondary coil 3 is constructed to givea'current of either low or high voltage, in accordance with thecharacter of heater employedi. e., whether a high or. low voltagecurrent is required to raise it to the desired temperature-and thewinding of this secondary coil is so proportioned that the wholeheater-circuit has a relatively large effective impedance, so that whenthe heater is operating alonethat is, before the pencil has beensufliciently heated to render it conductive and the pencil-circuit istherefore brokenthe flux of magnetic lines in the core isrelativelylarge-e. g.,.one hundredand the voltage on the primary coil 2is relatively large-e. g., five hundred.

The windings of the secondary coil 4: are so proportioned as to have arelatively small effective impedance, so that when the normal current isflowing through the pencil which is fed by it the current generated actsso as' to reduce the magnetic lines in the core 1 to a relatively smallfraction-e. g. ten-of what they were prior to the establishing of thecurrent through the pencil by heating the same. Consequently the voltageon 2 will be reduced in practically the same proportione. g., to fifty.It is characteristic of this construction that when the current flowsthrough the primary coil 2 on the closure of the switch 6 it,

will induce a large magnetic flux in the core 1, and the voltage thusinduced in the secondary coil 3say five volts if the heater isconstructed for low voltage-will drive a cur- In this construction theenergy spent in the heater will be approximately ten times that requiredto opcrate the heater, and hence the heating will be very rapid. At thesame time the large magnetic flux thus produced in the core will producea voltage in the secondary coil 4, and

therefore on the pencil, such voltage being approximately ten times thatrequired to normally operate the pencil. Hence a current will beestablished through the pencil much sooner than with an ordinary currentas now used. As soon, however, as the current begins to flow through thepencil the current generated in the secondary coil 4 will exert ademagnetizing effect. on the core 1 and the magnetic flux will graduallydrop until a nor-' mal current is flowing through the pencil, when theflux will be reduced, as above mentioned, to ten. The flux being thusreduced the voltage on the secondary coil-3 will hereduced to butoneienth, and consequently the current being reduced in the sameproportion only about one per' cent., approximately, of

the energy formerly used in the heater will now be effective therein.This small waste may be neglected, and it can be made as small asdesired by proper proportioning.

The reduction of the magnetic lines in the core, as above stated, willeflect a corresponding reduction of the voltage on the secondary coil 4and also on the primary coil 1. Thus the lamp is to a veryconsiderabledegree selfregulating, any excessive current in the pencil automaticallyacting to reduce the voltage on the primary coil and in the currentthrough the pencil.

As any-accidental opening of the'pencilcircuit in this form of lampwould cause a high voltage to be continuously kept up in theheater-circuit, and as at the same time there would be a great strain onthe insulation through the continuous heating of the heater and thesecondary coil 3, means should be provided whereby an automatic closingof Fhecircuit of the secondary coil 4 would be effected undersuchconditions. A convenient means to this end consists in so arranging'twoparts, as 9, of the circuit of the pencil so that they would. tend tospring together and form contact with each other and interposingbetweensuch parts 9 a suitable nonconducting material, as wax, whichwill become soft at comparativelylow temperatures and permit of themeeting of the two parts 9, thereby establishing a short circuit for thesecondary coil 4. The short circuit of this secaadary coil wouldpractically reduce the voltage on the primary coil to zero.

When a number of lamps of this character are used in series, as forstreet-lighting; it is preferred to light them in groups, say, of teneach, and to this end the circuit is arranged as shown in Fig. 6. Byturning the switch to the position shown in the drawings the lamps a inone group will be started, and as soouas the pencils have reachedincandescenje and the lamps are working properly the switch is shifted,thereby closing a circuit not only through the lamps previously light--[60, but also through the lamps b of the secend group. It willbe readilyunderstood that any number of groups may be arranged extending from a'single generator or from a In order to avoid thisobjecinonab making theheater, as it were, self-supporting an objectionable feature of theheaters as.

heretofore constructed is avoided, such heaters being usuallyconstructed of a comparatively small wire arranged upon a support, as aporcelain disk or cylinder, and connected thereto. It has been'fonndthat in practice the cement will soften, and the expansion of the wireas it is heated and cooled will cause it to become detached from andshift its position on the support, so that portions will contact, and,further, this form of heater is objectionable for the reason that thewires being-in contact with the support the latter will absorb a largeamount of heat and must be raised to the same temperature as the wiresand simultaneously therewith, so as to render the heater effective toraise the temperature of the pencil. The heating of the support as wellas the wires retards to an appreciable degree the'heating of the pencil.

It is preferred to so censtruct the heater or the'surface thereofadjacent to the pencilnthat the heat-waves will be caused to con vergeon the pencil. While not limiting myself tfpuch construction, I havefound that making the surface of the heater adjacent to the pencil toconform to the arc of a circle whose center coincides approximately withthe axis of the pencil giues highly satisfactory results. It ispreferred to cover the back of the heater with some non-conductingmaterial, which will prevent the loss of heat by radiation from thesurface opposite the pencil.

It has heretofore been the practiceto form the terminals of the pencilof some metal; but this construction is objectionable for the reasonthat the ends of the pencil will not become heated as rapidly as themiddle portion thereof for the reason that the metal con! ducts away theheat from the ends of the pen cil, and the latter will be conductive asreas regards its ends, for some time, smthat the lighting of the lamp ismaterially-"delayed.

feature, I employ a constructionsimilar to'thatmwn in Figs. 4 and 5. Astherein shown. the heater-circuit includes one or two tmasform ers,whose secondary coils 11 are wrapped around the ends of the pencil andserve to raise the temperature of these ends simultaneonsly with theheating of the middle portion bythe heater proper. As shown in Fig. 4, atransyormer is arranged at each end of the pencil, the primary coils 12of each transformer being included in the circuit of the secondary coil3 of the main transformer of 35 secondary coils 3 and 16 for theheaters.

the lamp, and the secondary coils ll of these pencil-transformersinclude in their circuit heaters formed by several turns of wire coiledaround the ends of the pencil. These coils on the ends of the pencilserve as the termi- [0 be employed.

In Fig. 7 I have shown an arrangement whereby the use of a separatetransformer or transformers for the heaters of the ends of the pencilsis avoided. In the arrangement of apparatus for the use of constantcurrents illustrated in Fig. 7 the heater 7 is included in the circuitof the secondary coil 3, such arrangement correspondingto that shown inFig. 2. One or more additional secondary 2o coils 16 are also wound onthe core 1 of the transformer, and heaters 17 for the ends of the pencilare included in the circuit or circuits of these additional secondarycoils. The secondary coil for the pencil may be in one section, as shownin Figs. 4 and 5, or in two connected sections 4*, as. shown in Fig. 7.The secondary coils 3 and 16 for the heaters are so proportioned as tohave a relatively large effective impedance, and the secondary 3o coilor coils for the pencil are proportioned to have a relatively smalleffective impedance. On the closure of the switch 6 a large magneticflux will be induced in the core 1, inducing a current of the desiredvoltage in the The large magnetic flux in the core will produce avoltage on the pencil. As soon as a current is established through thepencil the current generated in the secondary coil 4 will exert ademagnetizing effect on the core 1, so

that the magnetic flux will drop until a normal current flows throughthe pencil. This drop in the magnetic flux reduces the voltage on thesecondary coils 3 and 16 to such an extent that only a very small amountof energy will be efifect-ive in the heaters.

The construction shown in Figs. 1, 2, 4, and 5 is adapted for currentsof constant value. Where currents of constant voltage are employed, theconstruction shown in Figs. 8 and 9 is preferable. In this constructionthe magnetic flux in the core 1 remains practically constant at alltimes, and to efiect a regulation of or neutralization of theheater-cur- 5 rent so soon as a current begins toflpw nular core 14 andincluded in thegeneratorcircuit, as shown in Fig. 8, or in the circuitof a secondary coil 3 on the main transformer, as shown in Fig. 9. Theheater 7 is also included in the circuit of the coil 13. Another coil 15i's-falso wound on the core and is the circuit of the secondary coil 4.The terminals of the pencils are also included in the circuit of thecoils 4 and 15. In this construction the coil in series with theheater-circuit will give a back voltage amounting to a certainfraction-say ten per cent.-of that generated in the main feed-circuit orin the secondary coil 3 when there is no current through the secondarycoil The coil 15, in series with the pencil and secondary coil 4, is soproportioned that when the normal current is passing through the pencilthe coil 15 will operate on the coil 13 to produce in it a voltage equaland opposite in direction to that produced by the generator or the coil3, and the two voltages will thus neutralize each other, preventing theflow of current through the heater. When the switch 6 is closed, acurrent of suitable voltage from the generator or thecoil 3 flowsthrough the heater-circuit and rapidly raises the heater to a hightemperature. As an abnormally high voltage, owing to the constructiondescribed, is on the circuit of the pencil, it will begin to flowthrough the pencil when the latter is at a lower temperature than in theform of lamps now in use, so that the lamp becomes operative inaveryshort time.

When the current flows through the pencil, it reacts on and neutralizesthe current through the heater by generating an opposing voltage in theheater-circuit, thereby rendering the heater inoperative. This reactiveeffect is clearly distinguishable from the balancing or neutralizingaction of two primary coils on each other. The voltage on the pencilbegins to decrease as soon as the current passes through the pencil, asa part of the voltage will be used up in the coil 19.

As shown in Figs. 8 and 9, separate or auxiliary heaters may he appliedto the ends of the pencil in this system, as in that using a constantcurrent. As shown in Fig. 8, the heater 17 on the ends of the pencil areincluded in a circuit or circuits which include secondary coil or coils18 on the core of the main transformer and coil or coils 19' on the core14. The current which will flow through the pencil as soon as heatedwill neutralize the current in the auxiliary heaters .17 in the samemanner that it neutralizesthie current through the heateri. e., by thegeneration of voltages by the coil 15 equal to and opposing thosegenerated in the coils 18 of the priprimary transformer. In theconstruction shown in Fig. 9 the circuit of the secondary coil 3includes not only the coil 13 and the main heater, but also theprimarycoils 12 of the secondary transformer or transformers which havetheir secondary coils in series withthe heaters. 17 on the ends of thepencil. In this construction both heaters are operated by the coil 3 andcontrolled by the coil 15, which, as stated, will generate in-the coil13 voltages equal to and opposing those generated in coil 3 as soon ascurrent begins to flow through the pencil.

It 'will be understood by those skilled in the art that my improvementsmay be applied to the construction of lamp wherein the heater for thepencil consists of a conductor neutralizable by heat and extending alongthe pencil from terminal to terminal. Hence as regards the broaderclaims made herein the invention is not limited to any particular formor arrangement of heater, and, further, the means employed for heatingthe ends of the pencil may be used with other forms of lamp-i. (2.,those having the heater'in independent circuits-and hence that part ofthe invention is not limited as regards the numher or arrangement ofcircuits for the heater and pencil.

I claim herein as my invention- 1. In an incandescent lamp, thecombination of a pencil, a heater, a circuit for the pencil and acircuit for the heater, the current through the heater being reactivelyregulatcd by the current through the pencil, substantially as set forth.

2. In an incandescent lamp, the combination of a pencil, a heater,circuits for the pencil and heater and a magnetic circuit common to bothcircuits, said. circuits being so arranged and proportioned relativelyto each other, that the current. in the pencil-circuit acts onthe-common magne ic circuit in such way as to reduce the energy used forheating in the heater-circuit, substantially as set forth.

In an incandescent lamp, the combination of a pencil, a heater arrangedin operative relation to the pencil, a transformer hav: ing a primaryand secondary coils, the pencil being included in the circuit of one ofthe secondary coils, and the heater in the circuit of the othersecondary coil, whereby the heater-current is reactively regulated bythe pencil current, substantially as set forth.

4. In an incandescent lamp, the combination of a pencil, a heater forthe pencil, a transformer having a primary and secondary coils, thesecondary coils including in their circuits the pencil and heat-er, andmeans whereby the completion of the circuit through the pencil willneutralize the current through the heater, substantially as set forth.

5. In an incandescent lamp, the combination of a pencil, a heater forthe pencil, a transformer having a primary and secondary coils, the,secondary coils including in their circuits the pencil and heater, acore and coils on said core in series with the pencil and heatercircuits, substantially as set forth.

6. In an incandescent lamp, the combination of a pencil, electricheaters arranged in operative relation to the ends of the pencil,secondary coils including said heaters in their circuits and a primarycoil or coils for inducing currents in the secondary circuits,substantially as set forth.

7. In an incandescent lamp, the combination of a pencil, a circuittherefor, one or more heaters for the pencil, one or more circuitstherefor, and a magnetic circuitcomm on to the other circuits which areso related and proportioned that the current in the pencil-circuit actson the common magnetic circuit in such manner as to reduce the energyused for-"heating in the heater-circuit, substantially as set forth.

8. In an incandescent lamp, the combination of a pencil, one or moretransformers, electric heaters on the ends of said pencil included inthe secondary coils and a main heater included in the primary circuit ofthe transformer, substantially as set forth.

9. In an incandescent lamp, the combination of a pencil, a heater forthe pencil, a transformer having a primary and secondary coils includingin their circuits the 'pencil and heater,and means for automaticallyshortcircuiting the pencil-circuit, substantially as set forth.

In testimony whereof I have hereunto set my hand.

' REGINALD A. FESSENDEN.

Witnesses:

JNo. G. STEWART, J. O. ASHTON.

liiimtilituillrMlW

